"Any company that advertises definitely needs to target advertisements," says Gil Elbaz, who founded Factual, a location platform, as well as Applied Semantics, which launched AdSense and was later acquired by Google. "Famously, the ad industry has always dealt with half of your ad budget, while half is wasted, and the question is how can you use better targeting technologies to avoid that waste?"

All told, advertisers shelled out more than $42 billion last year for online, digital and mobile ads, according to the Interactive Advertising Bureau. Yet many aren't aware of certain industry tricks that can help maximize where, and exactly when, an ad gets exposure. Here are some tips from experts whospoke earlier this year at ClickZ Live Toronto, a digital marketing conference:

To address this gap, some businesses are creating marketing campaigns where coupons or ads only get sent to devices (like smartphones or tablets) if a shopper happens to walk within a geo-fenced area near a certain store or mall. "That ad would have the business location in it--it's highly targeted, and also very relevant, and we can walk you there," says Patel.

2. Time your ad's delivery.Prices for Web-based ads can vary widely depending on factors like who is selling the space, how large their real estate might be and where you'd like to display your message. Just don't forget to ask about when your ad might be displayed, as online traffic tends to peak during the weekdays between 7pm and 11pm local time, according to a Federal Communications Commission report.

And be on the lookout for unexpected deals. Earlier this year on MSN.com, for example, advertising tended to be much cheaper after 5pm "but it performed much better than any time of day, probably because people were done their jobs," says James Aitken, the CEO and co-founder of The Exchange Lab. (His company evaluates millions of audience interactions each day to identify the right audience--at the right time--for targeting campaigns.)

3. Define your campaign's goal.Here's the pitch: Around 1 billion tweets are being sent every couple of days, up from a full week in 2011, so why wouldn't you want to advertise with Twitter?

Be careful. There are different reasons why you might want to use the social media site. Some companies are fine with increased brand "engagement," which might mean additional hits to a site through link click-throughs. Many, however, prefer actual sales of their products or services. So it's worth digging into Twitter's conversation rate, which some have shown to be better than LinkedIn but worse than Pinterest and Facebook.

Brands that pay for promoted tweets generate six times as many clicks (though, again, not necessarily sales) as those that aren't promoted, and nine times as many re-tweets. And messages linked to a video, photo or some kind of freebie, such as one Target used to promote an exclusive edition of Justin Timberlake's latest album, also performed much better than text-only tweets. One particularly popular campaign from Starbucks lets people "tweet-a-coffee" to others, though it's not a tactic that many small businesses--like independent neighborhood cafes--would likely see traction from given their typically low volume of followers.

"These are compelling connections, but it requires work," Twitter Canada's CEO, Kirstine Stewart, said at ClickZ Live Toronto.

The opinions expressed here by Inc.com columnists are their own, not those of Inc.com.